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The structures of the liquid crystal (LC) molecules have a key role in impacting the electro-optical performance of a polymer dispersed liquid crystal (PDLC) film. In this paper, the relationship between the LC molecular structures and the electro-optical properties of PDLC films is investigated based on an unexplored cyano-terminated tolane compounds (CTTCs) doped E8 LCs/UV polymers system. Due to the high polarity of CTTCs, LCs doped with the cyano-terminated tolane (CTT) molecules exhibit high birefringence and large positive dielectric anisotropy. On the whole, PDLC films doped with the CTT molecules exhibit a lower driving voltage than that doped with the pure E8. More excitingly, PDLC films based on CTT molecules with larger length-to-width ratio and longer conjugated system show higher contrast ratio (CR) and faster response time. Eventually, the mechanism of the effects of CTT-based molecular structures and the relationship between the electro-optical performance of PDLC films and CTT molecules are illustrated. This work paves a new way for optimising the electro-optical properties of PDLC films. [ABSTRACT FROM AUTHOR]

To study effects of the crosslinking agent/diluents/thiol on morphology of the polymer matrix and the electro-optical properties of polymer-dispersed liquid crystal (PDLC) films, samples were prepared by ultraviolet (UV)-initiated polymerisation. Due to the interaction between thiol-acrylate reaction and acrylate monomers polymerisation, the sample compositions were the foremost determinant to the microstructures which in turn played an essential role on the electro-optical properties of the PDLC films. With the increasing content of the crosslinking agent, the LC droplet size decreased, while the thiol had a contrary effect on the LC droplet size. It was demonstrated that the superior properties of the low-driven voltage (37.2 V), the high contrast ratio (148.2), the short response time (14.9 ms) and the high saturation transmittance (86.6%) could benefit from a novel microstructure which had a dense surface and meshes with microspheres attached. It was of great significance for the optimisation and the potential applications of the PDLC films. [ABSTRACT FROM AUTHOR]

The different fluorinated liquid crystal (LC) molecules doped to E8 were used as LC component to prepare polymer dispersed liquid crystal (PDLC) films. The mass fraction of the LC mixture is fixed 50.0 wt%. Results indicate that doping 8.0 wt% fluorinated LC molecule ME3CP to E8 significantly reduced the driving voltage of the PDLC films, and the driving voltage reduced with the rise of mass fraction of ME3CP. Besides, the terminal flexible chain length of the fluorinated LC molecule influenced the LC mixture properties based on E8, such as the dielectric anisotropy, birefringence and viscosity of the LC mixture, and the morphology and the electro-optical properties of PDLC films were controlled not only by the physical properties of the LC mixture, but also by the terminal flexible chain length of the fluorinated LC molecule . [ABSTRACT FROM AUTHOR]

A photopolymerisable monomer/liquid crystal (LC)/chiral dopant/photoinitiator mixture with a smectic A (SmA*)-chiral nematic (N*) phase transition was prepared. After the SmA* phase was homeotropically oriented and then irradiated by ultraviolet light, a homeotropically oriented polymer network was formed in the SmA* phase and then a homeotropically oriented polymer network-stabilised liquid crystal (PSLC) film with a SmA*-N* phase transition was prepared. In the temperature range of the SmA* phase, the LC molecules were homeotropically oriented and the film exhibited a transparent state. However, in the temperature range of the N* phase, the film exhibited a strong light-scattering state owing to the fact that the LC molecules adopted a focal conic alignment affected by the homeotropically oriented polymer network. The strong light-scattering state of the N* phase could be changed into a transparent one when an electric field was applied. The focus of this study was on the effects of composition of the PSLC film on its thermo-optical and electro-optical properties. [ABSTRACT FROM AUTHOR]

Polymer dispersed liquid crystal (PDLC) films were prepared by thermal polymerization-induced phase separation in epoxy/polymercaptan/liquid crystal (LC)/accelerator mixtures. The effects of the concentration of LC and accelerator, the curing temperature, and the structure of epoxy monomer on the electro-optical (E-O) properties and adhesion strength of the PDLC films were studied systematically via E-O, peel strength, DSC, IR, and gel measurements. It showed that different polymer structures and the properties of the polymer can be obtained by changing the compositions and the curing temperature, which had significant impacts on the E-O properties of the PDLC films. Meanwhile, the polymer matrix with high glass-transition temperature (Tg) and small pore size will improve the adhesion strength of the PDLC film, and these kinds of epoxy-polymercaptan-based PDLC films have better performance than traditional acrylate-based PDLC in the aspect of the adhesion strength. This work may provide some inspiration in preparing epoxy-polymercaptan-based PDLC films, which both have excellent E-O performance and good adhesion strength, towards roll-to-roll processes and large-scale flexible applications. [ABSTRACT FROM AUTHOR]

As a smart dimming film, the polymer-dispersed liquid crystal film has potential application value in many fields. In this paper, an electrically controlled dimming film with a wide operating temperature range is investigated, which has fast response times and low driving voltage at −20 °C, and good shielding at 90 °C. The research can promote the application of the film in outdoor. [Display omitted] • The PDLC film has good electro-optical performances in the temperature range between −20 °C and 90 °C. • The working temperature of the PDLC film is broadened by using the liquid crystal with wide temperature range. • The effects of acrylate monomers and cross-linking agents on the working temperature of the PDLC film are investigated. • The influencing factors of the working temperature of the PDLC film are analyzed in detail. Polymer dispersed liquid crystal (PDLC) films have shown potential applications in various fields such as curtain walls, indoor partitions and smart windows due to their large-area and convenient manufacturing ability. However, the narrow working temperature range limits their outdoor applications, especially in automobiles. In this study, methods to improve the performances of PDLC films at high and low temperatures were explored. Liquid crystals (LCs) with wide temperature range were used and different polymerizable monomers and cross-linking agents matching the LCs were investigated. Results show that the prepared PDLC film has a better contrast ratio of 48 at a high temperature of 90 °C, and fast on-state and off-state response times of 74 ms and 895 ms at −20 °C, respectively, when using hexyl acrylate as monomer and 1,4-butanediol diacrylate as crosslinking agent. This research could promote the application of PDLC films to outdoor scenes like smart windows for automobiles. [ABSTRACT FROM AUTHOR]